1. Field of the Invention
The invention relates to a press apparatus that press-forms a steel sheet with a forming die, and a spray nozzle mounted to this press apparatus.
2. Description of Related Art
Typically, with vehicle parts and the like, a method for manufacturing a molded article by press-forming a steel sheet with a forming die is used. In this method, when press-forming a heated steel sheet, a method that involves quenching by cooling the steel sheet by spraying coolant onto the steel sheet from the forming die is employed. Therefore, a related press apparatus includes a supply passage that is provided inside a forming die and to which coolant is supplied, a spray hole that is communicated with the supply passage and is formed in a contact surface of the forming die that contacts the steel sheet, and a spray nozzle that is mounted to the spray hole. When coolant is supplied to the supply passage of the forming die when cooling the steel sheet, the coolant passes through the supply passage and is sprayed from the spray nozzle onto the steel sheet.
However, with the related press apparatus, a diffusion angle of the coolant from the spray nozzle is small so cooling efficiency is poor, which is problematic. To increase the diffusion angle of the coolant from the spray nozzle, it is necessary to increase the shape accuracy within the spray nozzle, which will lead to an increase in cost. In addition, when the shape accuracy within the spray nozzle is increased, the durability of the spray nozzle becomes a concern. Furthermore, 50 to 200 spray nozzles are used for one set of forming dies, so an increase in the cost of a single spray nozzle will greatly affect equipment costs.
Japanese Patent Application Publication No. 2007-229772 (JP 2007-229772 A) describes a hot forming die that press-forms a heated steel sheet (i.e., a compact), and cools the compact by spraying coolant onto it. This hot forming die includes a main supply passage through which coolant passes, a plurality of branch supply passages that branch off from the main supply passage and include spray ports that spray the coolant inside the die, and a nozzle member that is fixed to the spray port side of each of the branch supply passages, and limits the amount of coolant that passes through it using a passing hole through which the coolant passes.
However, with the hot forming die according to the invention described in JP 2007-229772 A, the diffusion angle of the coolant from the nozzle member is unable to be increased simply by fixing a nozzle member having a passing hole to the spray port, so the aforementioned problem is unable to be solved.